Author Topic: Touchstone Question  (Read 339 times)

dootmeng

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Touchstone Question
« on: July 11, 2017, 06:47:07 PM »
Hello all,

I'm currently in the process of building (verifying also I guess?) the Touchstone build. All is going well so far, however I have a point of clarification with regards to C17 (bottom LHS of schematic). C17 is supposed to be a bipolar electrolytic capacitor correct? Also, could I potentially substitute a  2.2 uf monolithic capacitor?

Also, with the 2.7 nf capacitor C10 (middle-ish RHS of schematic), would I be able to get away with using a 2.2 nf or perhaps a 3 nf capacitor.

I've attached the schematic below. Thanks all!


zombiesonore

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Re: Touchstone Question
« Reply #1 on: July 12, 2017, 03:39:30 AM »
Hi there,
for C17, why not using 2x1F Film capacitors in parallel?
for C10, I don't really know but I guess that, with a small different value, the effect will still work. Surely, if you have a 3n capacitor, it will work nicely.
Let us know!


somnif

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Re: Touchstone Question
« Reply #2 on: July 12, 2017, 03:49:28 AM »
I usually use MLCCs when a schem asks for 2.2uF. Mostly because I have them on hand and buying non-polar electrolytics seems superfluous. Hasn't been a problem yet.

And I'd agree with a 3nF working fine. Most film caps have 10+% tolerances so you could probably find one on the low side near 2.7 if you have a few on hand.

Monje

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Re: Touchstone Question
« Reply #3 on: July 12, 2017, 03:52:18 AM »
I had the same doubts about the 2.2uf condenser, and I ended up putting a multilayer.
I finished the circuit, I was testing, but it only comes out the clean sound of the guitar, it seems that it goes through the input buffer but it must go straight to the output, because it does not give any effect, I already changed the ic's by others of another lot but Nothing, the voltages of the ic's seem to me ok, I checked several times if I had no components changed or some short in the traces, but I do not have enough knowledge of electronics to know if I have any problems on my card, or if this layout has some error.
Has anyone successfully completed this circuit?

somnif

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Re: Touchstone Question
« Reply #4 on: July 12, 2017, 04:06:03 AM »
I had the same doubts about the 2.2uf condenser, and I ended up putting a multilayer.
I finished the circuit, I was testing, but it only comes out the clean sound of the guitar, it seems that it goes through the input buffer but it must go straight to the output, because it does not give any effect, I already changed the ic's by others of another lot but Nothing, the voltages of the ic's seem to me ok, I checked several times if I had no components changed or some short in the traces, but I do not have enough knowledge of electronics to know if I have any problems on my card, or if this layout has some error.
Has anyone successfully completed this circuit?

First question: Where did you get your MN3007? Bad/Fake chips have given me that symptom in other Chorus circuits. I had 10 from Ebay (thought I was getting a few good deals...) and even across 4 lots they were all toast. Blah.

Monje

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Re: Touchstone Question
« Reply #5 on: July 15, 2017, 08:40:42 AM »
Ok, thanks for the tip somnif, I bought it on ebay at one time 5, and another 10 chips, I already did several chorus circuits and none worked so far, I'm starting to get convinced that I have to throw all the chips in the trash.

bsoncini

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Re: Touchstone Question
« Reply #6 on: July 15, 2017, 01:43:24 PM »
Honestly. Those bbd chips for analog delay and chorus pedals you wanna buy from a reliable source. They are expensive but they work.

Monje

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Re: Touchstone Question
« Reply #7 on: July 19, 2017, 05:13:07 AM »
It works!!!
 The chorus is perfect, I just need to change the fake MN3007 to another one that arrived yesterday, I changed the chip, I turned the trimmer a little bit (it was practically in the middle), as soon as I heard a metalic sound I stopped. I started to play, and I could not stop.
Below is the image of the chips.

« Last Edit: July 19, 2017, 05:31:25 AM by Monje »